The present invention relates generally to the field of internal combustion engines and, more particularly, to the control of an internal combustion engine of a locomotive to reduce the adverse effects of ambient air temperature changes on the performance of the engine.
Locomotives operated in the far north and south regions of the globe are subject to severe winter weather conditions, including cold temperatures, and blowing and drifting snow. It is known that snow may be drawn into the air inlet ducts of a locomotive and may accumulate in sufficient quantities to obstruct the passage of air through the ducts. It is not uncommon for snow to accumulate on air filters disposed in the air inlet pathway of a locomotive. Such accumulations of snow may reduce the power output of the engine or cause it to cease from operating completely.
It is known to provide summer/winter doors in a locomotive which function to connect the air inlet duct with a source of warm air so that the cold ambient air is mixed with relatively warmer air prior to passing through the final air filters. If the temperature of the inlet air mixture can be maintained above the freezing point, any snow that may be deposited on the filters or ductwork will melt rather than accumulating to the point of restricting intake air. The name "summer/winter" has been applied to these doors because in the prior art they were manually operated using a simple rule of thumb, such as open in the winter and close in the summer. Warm air is available in the engine compartment of a locomotive because radiant and convected heat from the engine tends to raise the air temperature around the engine. Because of the need to protect components such as wires, hoses and fuel lines from high temperatures, locomotive engine compartments are normally ventilated. It is known to pass the exhaust air from an equipment cabinet of the locomotive into the engine compartment to provide such ventilation. The exhaust from an equipment cabinet contains filtered and slightly pressurized air from an equipment blower, and it passes out of the equipment cabinet at a relatively low temperature. This air is exhausted through the engine compartment and into the combustion air intake ductwork through the summer/winter doors.
It is known to increase the flow of warm air from the engine compartment to the inlet air supply ductwork by at least partially restricting the ambient air inlet openings when the summer/winter doors are opened. By simultaneously restricting the inlet of cold ambient air when the winter/summer doors are opened, the percentage of warm air drawn into the engine is increased. The use of such doors also helps to maintain the original air velocity through any upstream inertial filters. By maintaining the air velocity through the inertial filters, the efficiency of the inertial filters in removing snow from the intake air is maintained.
There is a continued demand for improved performance of locomotive engines, in terms of fuel economy, component loading, power output and reduced emissions. To achieve such optimized performance, the conditions of combustion within the internal combustion engine needs to be controlled. However, engine designs are limited because of the extremes of environmental conditions under which a locomotive must operate. For example, cylinder peak firing pressure may become too high as the engine is operating during cold days when the inlet air temperature is very low, thus generating excessive stress on engine components. Alternatively, cylinder exhaust temperatures may become too high as the engine is operating during hot days when the inlet air temperature is very high, thus causing turbocharger damage due to overheating and overspeed. Very high inlet air temperature may also increase engine exhaust emissions such as smoke, carbon monoxide (CO), and particulate matter (PM).